The candidate is trained in applied mechanics, physiology, systems analysis, and experimental and theoretical microcirculatory physiology. His immediate career goal is to establish a productive experimental and theoretical microcirculatory research laboratory at the University of Virginia. His long-term goals are to obtain a tenured position in a high-quality Biomedical Engineering department and to pursue research in biomechanics of microvascular function. An RCDA award would allow him to devote a substantial period of time to scientific work at a stage in his career when research funding is assured, but his time would be subject to increased teaching and administrative demands. The RCDA would thus allow productive use of available research funds, production of a body of significant work, and possible achievement of a tenured position. These goals are consistent with the institution's development plans, as Biomedical Engineering plans to establish a center for Cardiopulmonary Engineering, with basic research in organ transport phenomena as an emphasis. The specific objective of this study is to test the hypothesis that intravascular stresses, namely blood pressure and wall shear stress, play a role in determining the sites and magnitudes of vessel growth. The specific aims are to measure the remodelling of the microvasculature in the gracilis muscle of the rat during normal maturation of WKY rats and during development of hypertension in SHR and to relate the observed remodelling to the hemodynamic stresses acting in the network. Application of this data in a network model will make it possible to test the hypothesis that the elevated resistance in spontaneous hypertension is an adaptation to changes in hemodynamic conditions, but is based on a common growth principle.